Unlike traditional cigarettes and similar tobacco products, e-cigarettes, or smokeless cigarettes, are not banned by Ohio law in public and private places, leaving it up to businesses and governmental agencies to set their own policies.

Anita Keller, owner of Hungry Soul Cafe in downtown Columbus, is an e-cigarette user in her own restaurant and doesn't discourage patrons from doing the same.

So far, she sees it as a non-issue.

"We as a business are open to the use of the devices in our establishment, as they are not offensive in any way and they allow our clientele the freedom to 'smoke' without offending other guests," she said.

Colin Gawel, owner of Colin's Coffee in Grandview Heights, is taking a wait-and-see approach to the issue. He said he's noticed only one customer dragging on an e-cigarette and chose to ignore it.

"I've never said anything," he said. "I've never noticed the smoke or smelled anything. If it's not bothering anyone else, I guess I have no problem with it."

Some local governmental agencies have responded to the e-cigarette trend.

The Columbus Metropolitan Library board, for example, voted in October to ban e-cigarettes from all facilities, meaning customers and staff must exit the building if they want to use them.

"While there were a few instances of staff observing customers using e-cigarettes shortly after they became popular, CML's board wanted to be proactive in preventing customer and staff exposure to this product in the event they prove to be harmful to others," said Gregg Dodd, marketing director for the library system.

Likewise, Columbus Public Health prohibits e-cigarette use inside its building on Parsons Avenue, but has not taken an official position on the matter.

"Our current efforts do focus on promoting tobacco-free living through prevention, cessation and encouraging tobacco-free policies that include e-cigarettes," said Jayne Moreau, spokeswoman for the health agency.

There's a bill pending in the Ohio legislature that would prohibit those under 18 from buying e-cigarettes. Similarly, Upper Arlington City Council is considering a ban on the sale of e-cigarettes to minors.

Here's how e-cigarettes work: A cartridge filled with liquid containing nicotine is placed into an electric device, often resembling a traditional cigarette.

Heat from a battery creates a vapor, which is inhaled by the user. It requires no lighter or match, and releases no smoke.

Miguel Martin, president of Logic, one of the largest e-cigarette manufacturers in the U.S., said his company has made many concessions to keep e-cigs out the reach of youngsters.

LOGIC does not advertise on TV, has no celebrity endorsements and has discontinued flavored products, Martin said.

The company discourages online sales of the devices, although maintains a website that allows users to purchase e-cigarettes through a comprehensive vetting system, he said.

Martin said LOGIC has implored national health agencies – the Centers for Disease Control and Prevention, National Institutes of Health and the Federal Drug Administration – to conduct comprehensive testing free of tobacco money to determine its effect on public health.

"What we believe is critically important is informing adults and let them make an educated decision," Martin said.

The American Lung Association said there's plenty of cause for concern.

In initial lab tests conducted in 2009, the FDA found detectable levels of cancer-causing chemicals – including an ingredient used in antifreeze – in two leading brands of e-cigarettes and 18 various cartridges, said Erika Seward, assistant vice president of national advocacy for association.

The lab tests also found that cartridges labeled as nicotine-free had traceable levels of nicotine, Sward said.

Studies have found formaldehyde, benzene and tobacco-specific carcinogens, or cancer-causing agents, in the secondhand emissions of e-cigarettes, she said.

With 250 different brands of e-cigarettes available, it's difficult to know what other substances might be present, she said.

"The American Lung Association is very concerned about the potential public-health impact of e-cigarette use," she said.

"The lung association is alarmed at the doubling of use of e-cigarettes among youth, and the unsubstantiated therapeutic claims being made by some manufacturers.

"It is critical that the White House give the FDA the green light to begin its oversight of e-cigarettes, cigars and other unregulated tobacco products."

Naturally, the industry has its advocates, and with competing studies.

The Consumer Advocates for Smoke-free Alternatives Association, based in suburban Washington D.C., is opposed to bans of e-cigarettes of indoors.

Elaine Keller, president of CASAA, said it commissioned a study from the Drexel University School of Public Health that showed e-cigarettes pose no health concern for users or bystanders.